Enhanced biological stability of collagen with incorporation of PAMAM dendrimer

The crosslinking methods of collagen using glutaraldehyde (GTA) and 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS) are frequently performed in biomedical applications, but both methods still have their own disadvantages, including the GTA cytotoxicity and low degree of EDC/NHS crosslinking. In this study, we incorporated polyamidoamine (PAMAM) dendrimer with surface amine groups into the two aforementioned crosslinking methods to improve the biostability and structural integrity of collagen. Fifty micromolar of dendrimer concentration was found to have negligible in vitro cytotoxicity and was used for EDC and GTA crosslinking of collagen. The collagenase digestion assay showed that the collagen scaffolds crosslinked in the presence of PAMAM exhibited a higher denature temperature and higher resistance against collagenase digestion compared with their counterparts without dendrimer. Cell proliferation with human conjunctival fibroblasts showed that the incorporation of PAMAM in EDC crosslinking significantly increased the proliferation. All the crosslinked scaffolds also exhibited higher structural stability than the noncrosslinked scaffold. Crosslinking with EDC and PAMAM together yielded substantially higher proliferation and may be a suitable collagen scaffold for biomedical applications. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 91A: 114-122, 2009